Progress!

You'll have the CIS gauges on Monday so you can check your fuel pressures.

HF carries the MityVac handheld pumps. They're pretty inexpensive as I recall. That's all you need to test the AAV.

You can bench test the AAR a couple of different ways. When you have it out of the car, it should be mostly open -- i.e., you should be able to easily see through it. The best approach is to connect it to a 12v power source so you can test that it is functioning correctly when power is applied. It should almost completely, but not quite, closed. You can heat it with a hair dryer to get the same effect, but again, you won't be testing that it is working from applied voltage -- just engine heat.

I thought for sure when you fixed that pipe leak you would've eliminated your noise.

Can you 'hold' a RPM, e.g. 3000 RPM, using the throttle pedal and prevent the engine
from dying when warm? If so and the engine runs smoothly, then the control and
system pressures are close to their proper values. This would also eliminate the possibility
of a major intake air leak. This would also determine whether you still have an ignition
problem, e.g. the CDI unit, when the warm mode occurs.

This morning I did the easy check on holding RPM high. At 39 seconds after cold start, the idle drops to close to 1K (presumably thermal valve kicking in). At about 2 minutes, idle drops below 900 and it wants to stall. At this point I held the throttle down (in the engine bay).
For the next 8 minutes, I kept holding the throttle to keep RPMs 2-4K. If I held a consistent throttle level, the RPMs were consistent. Possibly slowly dropped over that time, but I'm not sure. Responded quickly to revving. However ran rough, and had an intermittent "stutter" that was clear when leaning over the engine, but might not have been obvious from further away. Sort of like the occasional stutter which occurs when RPMs drop low during an actual stall.

I got a vacuum pump now. This afternoon I'll go after the AAR and AAV! I should just be able to use my car battery as the 12V source, assuming I can rig up a decent connector.

That's good progress. You can eliminate both the AAR (cold start fast idle) and the
AAV (start idle-up) valves by pinching their lines when you hold the RPM as you just
did and determine if they're affecting the running. You might also try and adjust
the mixture screw while holding the idle, i.e. after the engine warms. Obviously
without knowing what the control pressure is, this adjustment may need further
tweaking later. But at least you'll know whether the higher RPM running can be
smoother with a tweaked mixture.

Again, both the AAV & AAR draw intake air thru the sensor plate and just bypass
the throttle body butterfly, so they don't affect the mixture. Once the throttle
is open, e.g. > 2K - 3K RPMs, both valves have little effect compared to the throttle
butterfly position in determining the RPM. This assumes that neither valve has an external
leak, i.e. very rare.

I tried getting it warm by holding the idle high. Then I turned it off and blocked off the AAR/AAV hose where it goes into the spaceship boot. After that, it wouldn't start (although I did get somethng of a backfire). One of the hoses is aluminum, and the other is a large radius very thick rubber, so I'm not sure how to pinch them off. Presumably the AAV is still needed to start, so my test wasn't definitive.

Any tricks to doing the pinch-off?

I'm hoping to avoid taking the system apart again to test the AAV with the vacuum pump, but its not the end of the world if I have to.

Neither the AAV nor the AAR is needed to start the engine, i.e. they avoid having to
depress the throttle pedal to start and maintain an idle when cold, respectfully.
They function the same as if you depressed the throttle pedal during and after
starting.

Ok, so if it won't warm-start with throttle open the AAV/AAR pipe blocked blocked off, the problem is somewhere else. Correct? Having eliminated the air sources, it is looking like that fuel pressure gauge is going to be real handy tomorrow.

Got the gauges, ran some tests, here is what we've got.
Setup - removed the top fuel connection at the WUR (not the banjo, but the one coming from the fuel distributor). Placed the gauge between the end of that fuel hose and the WUR's connection. Ambient temperature was 77 F (25 C). I bled the gauge before testing. All tests with vacuum lines connected.

[Fuel Distributor]---{normal hose}---[connector]---{fuel gauge hose}---[Gauge T junction]---{fuel gauge hose}---[WUR]

System Pressure
(Engine off, FP running, gauge valve CLOSED, cold engine at about 25 Celsius (presumed matching outside))
4.7 Bar

Control Pressure #1
Engine off, FP running, gauge valve OPEN, engine cold
1.0 Bar

Control Pressure #2
Engine running, gauge valve OPEN, immediately after first engine start of the day
1.3 Bar

At this point the engine idled on its own. However within about a minute it started losing RPM and wanted to stall. I held the throttle open by hand.

Control Pressure #3
Engine running, gauge valve OPEN, after about 6-7 minutes running
2.3 Bar

While approaching this #3 reading, I occasionally revved the engine. The control pressure would rise to around 3.0 Bar when I revved. Whilst changing hands to hold the throttle open, the throttle closed some and dropped to about 600 RPM. Although I opened it back up right away, it seemed to be no longer firing properly, and would vibrate the engine. I got the RPM to raise up to about 1500 RPM, but the idle never smoothed out. Within about a minute, I was no longer able to keep RPM up and it stalled. Then it would not start. This is typical behavior I am experiencing.

The Bentley specifies a system pressure of 4.5-5.2 Bar, so my 4.7 is within spec.
The Bentley gives two graphs for Control Pressure (see below), depending on your control pressure regulator. My '79 could be either of these two models. Regardless of which it is, my reading of 1.3 Bar is bad. I didn't have a gauge on it, but if it rose even 10 degrees C in 7 minutes, it should have been over 2.5 Bar, and it was only at 2.3 Bar.

At 25 C, the reading should be:
Graph 1) 2.2-2.7 Bar
Graph 2) 2.1-2.5 Bar

http://forums.pelicanparts.com/uploa...1436225628.jpg

This was a few days after resetting the mixture adjustment. In that reset, I put injectors in baby bottles and ran the Fuel Pump (engine off), and turned the mixture until it sprayed the injectors with the sensor plate at rest. Then turned it back a bit to stop the spraying/leaking. I've adjusted it a little since then, but I am pretty sure I have returned it to that setting each time.

So in other words your control pressure is 1 bar (or 30%) too low all the times - that would make it run rich all the times, correct?

If I understand your write-up you started at barely ~1.0 bar (very low) and came up to only ~2.3 bar (too low) after several minutes of running.

In contrast the manual specifies to be around 2.3 bar cold and come up to somewhere around 3.3 bar warmed up.

That was my conclusion as well. I'm reading through Jim's Basement Workshop pages trying to find the next course of action.

Yes, the control pressure is a little low when cold, i.e. it should be 1.5, and higher
when fully warm (3.3) resulting in the mixture now being a too rich. You should be able
compensate for this by leaning the mixture with mixture screw temporarily at a constant
RPM to keep it running. The engine, though, won't accelerate properly but your test
at this point is to see if you can keep the engine running and eliminate the CDI unit
as a potential source of your problems. You can also move the sensor plate arm
to lean the mixture when you think it's going to die to keep it running temporarily.

To lean the mixture by increasing the control pressure, you can lightly tap on the round
pin on the WUR. As you lightly tap on the pin, monitor how the control pressure changes
when cold. If you tap too hard, the WUR must be disassembled to re-position the pin
so be careful.

Make sure that you have power coming to the WUR (gets power when the FP runs)
or the control pressure will not increase properly as the engine warms. The WUR
does warm-up from the engine case as the engine warms, but not enough unless
the ambient/engine is really hot.

Back to your initial post:

Here the engine was running fine until the CDI died. Unless the WUR was adjusted
or the fuel pressure regulator pressure changed during the recent troubleshooting,
the fuel system should now be the same and unaltered from when the engine ran fine.
So maybe the control pressure needs some tweaking now, but the engine ran fine!

Again, think about what fuel system elements, if any, that you may have changed
relative to the initial fuel system setup.

Since the original post, you've adjusted the mixture and found/fixed a bunch of vac leaks. Since the fuel pressures are telling you that your base setting was rich, the false air was probably having the effect of leaning the mixture out closer to normal. Now that you've eliminated the false air, you're probably too rich.

Like Dave said, you can adjust the pin to raise the control pressure. You just need to run the fuel pump while you do that so you can monitor the pressure changes.

Once that's fixed, you'll need to adjust your idle and mixture and verify your timing.

You said you still had the "woo" sound though. I'm still surprised by that. Any idea what that pipe was rubbing against to wear down that hole?

So let me make sure I understand this correctly.

Currently, engine off, FP running, gauge valve OPEN, engine cold was reading 1.0 Bar. Do I begin pin adjustment with this setup? See if I can get it to about 1.5 Bar?

Or do I start the car and adjust from there? I'll have only a couple of minutes before she begins to stall out (assuming I don't solve the problem quickly.)

I'll probably only get 2 shots at it tonight, if it involves the engine getting warm and needing to cool off again.

Start with this:
- cool engine
- engine OFF
- fuel pump RUNNING
- gauge valve OPEN
- 12v to WUR DISCONNECTED

This should give you cold control pressure. Lightly tap the WUR pin down to adjust the pressure up to 1.5 bar. Like mysocal911 said, if you go too far you have to take the WUR apart to move the pin back up so be careful. You might want to turn the FP off while you make adjustments and then turn it on again.

Take a multimeter and set it to Ohms and clip one lead to each of the male 12v terminals on the WUR. You should measure a value in the 25-26 Ohm range. Let us know if you get something drastically different.

Once you've adjusted the cold control pressure, plug in the electrical connection to the WUR and see what the warm control pressure increases to and record how long it takes.

That should get you back in the normal range.

After that you can test your residual pressure. Turn the fuel pump off and record the pressure at 1min, 5min, 10min, 15min and 30min intervals. Records those values. If the fuel pressure drops off significantly that means you'll have warm starting issues.

Once you've done all that, try starting the car normally. If it will run consistently for a good 10 minutes (even if it's not smooth), you want it to get warmed up before you start adjusting the idle and the mixture. You may need to check/adjust your timing too -- it all depends on how far off the other adjustments were when you started.

I have found that a wideband O2 sensor is a fantastic tuning tool for taking the guesswork out of the "am I too rich/lean?" question, but you don't have the Lambda system so that's not an easy option for you.

Follow Tim's detailed guideline for setting up the fuel system, and you'll eliminate the fuel system
as a problem source in your troubleshooting.

If cold pressure is currently/truly at 1 bar, you need to take apart the WUR and press the post out. It is already adjusted too rich. (Tapped In too far)

Ah, now we are getting somewhere. I found the same instructions elsewhere: if the control pressure is off with the engine cold the culprit is the WUR (aka: control pressure regulator).

- first, you might have to check if the WUR is simply bad and RR it (^^^ timmy's post)
- Next, did you ever check whether your heating element works (Ohm meter) and whether there is current flowing through the WUR?

Ingo

I'll start testing when I get home in a few hours. Checking the heating element seems easy enough.

I'm a little confused on if I should push the pin in further (timmy's advice) or take the WUR out and push the pin further out (tirwin's input).

EDIT - Whoops, switched names.
tirwin: "... Lightly tap the WUR pin down to adjust the pressure up to 1.5 bar. Like mysocal911 said, if you go too far you have to take the WUR apart to move the pin back up so be careful..."

timmy: "If cold pressure is currently/truly at 1 bar, you need to take apart the WUR and press the post out. It is already adjusted too rich. (Tapped In too far)"